1. Field of the Invention
The present invention relates to a circuit component built-in module. In particular, the present invention relates to a circuit component built-in module in which, for example, an active component is arranged in an internal portion of an insulating substrate.
2. Description of the Prior Art
Recently, with a demand for high performance and miniaturization of electronic equipment, high-performance and high-density circuit components have been increasingly desired. This leads to a demand for a circuit substrate commensurate with high-performance and high-density circuit components.
The formation of a multilayered circuit may be a solution to achieve higher-density circuit components. However, a conventional glass-epoxy substrate requires a through-hole structure to form a multilayered circuit, to that is hardly a solution for high-density mounting. Therefore, a connection method using inner via holes that can connect between wiring patterns of LSIs or circuit components in the shortest distance has been developed in various fields in order to achieve higher density packaging.
The connection method using inner via holes allows electrical connection only between the layers necessary to be connected through a connection called an inner via, so that circuit components can be mounted with high density (U.S. Pat. Nos. 5,481,795, 5,484,647, and 5,652,042).
However, a substrate that has been conventionally used in the inner via connection comprises a resin based material, which has low thermal conductivity. Therefore, the problem of a low thermal conductivity is posed. In a circuit component built-in module, the higher density mounting of circuit components leads to an increased demand for releasing heat that has been generated in the components. However, the conventional substrate cannot sufficiently release heat, and therefore, the reliability of the circuit component built-in module deteriorates.
It is the object of the present invention to provide a highly reliable circuit component built-in module in which circuit components are mounted with high density, and a method for producing the same.
A first circuit component built-in module of the present invention includes an insulating substrate formed of a mixture comprising 70 wt % to 95 wt % (on the basis of the mixture) of an inorganic filler and a thermosetting resin; a plurality of wiring patterns formed on at least a principal plane of the insulating substrate (one wiring pattern consists of a group of electric lines formed on the same plane); a circuit component arranged in an internal portion of the insulating substrate and electrically connected to the wiring patterns; and an inner via formed in the insulating substrate for electrically connecting the plurality of wiring patterns.
The first circuit component built-in module allows circuit components to be mounted with high density, because the inner via formed in the insulating substrate establishes inner-via-hole connection.
Furthermore, the first circuit component built-in module allows circuit components to be mounted with further higher density by mounting circuit components on the wiring patterns formed in an internal portion of the insulating substrate.
Furthermore, the first circuit component built-in module constitutes a highly reliable circuit component built-in module, because heat generated in the circuit components is released promptly by the inorganic filler.
Furthermore, the first circuit component built-in module allows the heat conductivity, the coefficient of linear expansion, the dielectric constant, the breakdown voltage or the like of the insulating substrate to be changed in accordance with the circuit components by selecting a suitable inorganic filler. When the circuit component built-in module includes a semiconductor device and a chip capacitor, noise in electric signals can be reduced by reducing the distance between the semiconductor device and the chip capacitor.
In one embodiment of the first circuit component built-in module, the wiring patterns are preferably formed on the principal plane and in an internal portion of the insulating substrate. Mounting circuit components on the wiring patterns formed in an internal portion of the insulating substrate further increases the density in the circuit components.
In one embodiment of the first circuit component built-in module, the circuit component preferably includes an active component, and the inner via is preferably formed of a conductive resin composition. A circuit component having a desired function can be formed by including an active component in the circuit components. When the inner via is formed of a conductive resin composition, the production of the circuit component built-in module can be facilitated.
In one embodiment of the first circuit component built-in module, the circuit component is preferably shielded from external air by the insulating substrate. Shielding circuit components from external air prevents the reliability of the circuit components from deteriorating, which otherwise might deteriorate due to humidity.
In one embodiment of the first circuit component built-in module, the thermosetting resin preferably comprises at least one thermosetting resin selected from the group consisting of an epoxy resin, a phenol resin and a cyanate resin. These resins are excellent in heat resistance and electrical insulation.
In one embodiment of the first circuit component built-in module, the inorganic filler comprises at least one inorganic filler selected from the group consisting of Al2O3, MgO, BN, AlN and SiO2. Use of these inorganic filler provides an insulating substrate having an excellent heat dissipation. When MgO is used for the inorganic filler, the coefficient of linear expansion of the insulating substrate can be raised. When SiO2 (especially, amorphous SiO2) is used for the inorganic filler, the dielectric constant of the insulating substrate can be reduced. When BN is used for the inorganic filler, the coefficient of linear expansion of the insulating substrate can be reduced.
In one embodiment of the first circuit component built-in module, an average particle diameter of the inorganic filler is preferably 0.1 xcexcm to 100 xcexcm.
In one embodiment of the first circuit component built-in module, the wiring patterns preferably comprise at least one conductive substance selected from the group consisting of copper and a conductive resin composition. Since copper has a small electrical resistance, fine wiring patterns can be formed by using copper. Furthermore, electric lines can be formed easily by using a conductive resin composition.
In one embodiment of the first circuit component built-in module, the wiring patterns preferably comprise lead frames formed by etching or stamping. The metal lead frame has a low electric resistance. Etching allows the formation of fine wiring patterns. Stamping allows formation of the wiring patterns with simple equipment.
In one embodiment of the first circuit component built-in module, the circuit component preferably comprises at least one component selected from the group consisting of a chip resistor, a chip capacitor and a chip inductor. A chip component can be readily buried in the insulating substrate.
In one embodiment of the first circuit component built-in module, preferably, the mixture further comprises at least one additive selected from the group consisting of a dispersant, a coloring agent, a coupling agent and a releasing agent. A dispersant serves to disperse the inorganic filler in the thermosetting resin uniformly and sufficiently. A coloring agent serves to color the insulating substrate, so that the heat dissipation of the circuit component built-in module can be improved. A coupling agent serves to raise the adhesion between the thermosetting resin and the inorganic filler, so that the insulating property of the insulating substrate can be improved. A releasing agent serves to improve the releasing property of the mold and the mixture, so that the productivity can be raised.
In one embodiment of the first circuit component built-in module, the insulating substrate preferably has a coefficient of linear expansion of 8xc3x9710xe2x88x926/xc2x0 C. to 20xc3x9710xe2x88x926/xc2x0 C. and a heat conductivity of 1 w/mK to 10 w/mK. A heat conductivity close to that of a ceramic substrate can be obtained, and a substrate having high heat dissipation can be obtained.
In one embodiment of the first circuit component built-in module, the active component preferably comprises a semiconductor bare chip, and the semiconductor bare chip is preferably flip-chip bonded onto the wiring pattern. The flip chip bonding of the semiconductor bare chip allows high density mounting of semiconductor devices.
In one embodiment of the first circuit component built-in module, the conductive resin composition preferably comprises, as a conductive component, metal particles of at least one metal selected from the group consisting of gold, silver, copper and nickel, and an epoxy resin as a resin component. The above-listed metals have low electric resistances, and an epoxy resin is excellent in heat resistance and electric insulation.
A first method for producing a circuit component built-in module includes the following steps: processing a mixture comprising 70 wt % to 95 wt % (on the basis of the mixture) of an inorganic filler and an uncured thermosetting resin into a first sheet having a through-hole; filling the through-hole with a thermosetting conductive substance so as to form a second sheet having the through-hole filled with the thermosetting conductive substance; mounting a circuit component on a wiring pattern portion in a first film; positioning and superimposing the second sheet on the side of the first film where the circuit component is mounted, and superimposing a second film having a wiring pattern portion on the second sheet, thereby forming a third sheet in which the circuit component is buried; and heating the third sheet so as to form a fourth sheet in which the thermosetting resin and the conductive substance are cured.
According to the first method, the circuit component built-in module of the present invention can be produced easily.
A second method for producing a circuit component built-in module of the present invention is directed to a method for producing a circuit component built-in module having a multilayered structure. The second method includes the following steps: processing a mixture comprising 70 wt % to 95 wt % (on the basis of the mixture) of an inorganic filler and an uncured thermosetting resin into a first sheet having a through-hole; filling the through-hole with a thermosetting conductive substance so as to form a second sheet having the through-hole filled with the thermosetting conductive substance; forming a wiring pattern on a principal plane of a release film and mounting a circuit component on the wiring pattern; positioning and superimposing the second sheet on the principal plane of the release film, and pressing the second sheet together with the release film provided with the circuit component, thereby forming a third sheet in which the circuit component is buried; peeling the release film from the third sheet so as to form a fourth sheet; and positioning and superimposing a plurality of sheets produced in the same manner as the fourth sheet on one another with a film including a wiring pattern portion on top of the plurality of sheets, and pressing and heating the plurality of sheets and the film, thereby forming a fifth sheet having a multilayered structure in which the thermosetting resin and the conductive substance are cured.
According to the second method, the circuit component built-in module having a multilayered structure of the present invention can be produced easily.
In one embodiment of the first and second methods for producing a circuit component built-in module, the circuit component preferably comprises an active component, and the conductive substance comprises a conductive resin composition. A circuit component having a desired function can be formed by including an active component in the circuit components. Furthermore, when the conductive substance comprises a conductive resin composition, it is easy to fill a through-hole with the conductive substance and to cure the conductive substance. Therefore, the production is facilitated.
In one embodiment of the first and second methods for producing a circuit component built-in module, the first and second films are formed of copper foils, and the method further comprises the step of removing the copper foil in a portion other than the wiring pattern portions so as to form wiring patterns after the step of forming a sheet in which the thermosetting resin and the conductive substance are cured. This step facilitates the formation of the wiring pattern on the principal plane of the insulating substrate
In one embodiment of the first and second methods for producing a circuit component built-in module, the first and second films are formed of release films on one principal plane of which wiring patterns are formed, and the method further comprises the step of peeling the release films from the sheet, after the step of forming a sheet having the thermosetting resin and the conductive substance cured. This step facilitates the formation of the wiring patterns on the principal plane of the insulating substrate.
In one embodiment of the first and second methods for producing a circuit component built-in module, the method further includes the step of injecting a sealing resin between the copper foil or the wiring pattern and the circuit component after the step of mounting the circuit component in the copper foil or the wiring pattern. This step prevents gaps from being formed between the circuit component and the wiring pattern, and strengthens the connection between the circuit component and the wiring pattern.
In one embodiment of the first and second methods for producing a circuit component built-in module, the thermosetting resin and the conductive substance are preferably heated at 150xc2x0 C. to 260xc2x0 C. for curing. The heating in this range of temperatures can cure the thermosetting resin without causing damage to the circuit component.
In one embodiment of the first and second methods for producing a circuit component built-in module, the thermosetting resin and the conductive substance are preferably pressed at a pressure of 10 kg/cm2 to 200 kg/cm2 while being heated for curing. Pressing while heating provides a circuit component built-in module having an excellent mechanical strength.
In one embodiment of the first and second methods for producing a circuit component built-in module, the step of forming the first sheet further comprises the step of heating the sheet mixture at a temperature below a cure temperature (e.g., a temperature lower than a cure starting temperature) of the thermosetting resin, thereby eliminating the adhesion of the sheet mixture after the step of forming the mixture into the sheet. A subsequent process can be facilitated by eliminating the adhesion of the sheet mixture.
In one embodiment of the first and second methods for producing a circuit component built-in module, the step of forming the third sheet by burying the circuit component in the second sheet is preferably performed at a temperature below a cure temperature of the thermosetting resin. When the step is performed at a temperature below a cure temperature of the thermosetting resin, the thermosetting resin can be softened without being cured. This embodiment makes it easy to bury the circuit component in the second sheet, and also makes it to provide a smooth surface to the circuit component built-in module.
In one embodiment of the first and second methods for producing a circuit component built-in module, the step of mounting the circuit component on the wiring pattern comprises the step of electrically and mechanically connecting the circuit component and the wiring pattern with solder. This embodiment prevents poor connection between the circuit component and the wiring pattern due to heating that is performed to cure the thermosetting resin.
In one embodiment of the first and second methods for producing a circuit component built-in module, the step of mounting the active component on the wiring pattern comprises the step of electrically connecting a gold bump of the active component and the wiring pattern with a conductive adhesive. The use of a conductive adhesive prevents poor connection or dislocation of components from occurring at a subsequent step of heating.
As described above, the circuit component built-in module of the present invention employs the insulating substrate comprising a mixture of an inorganic filler and a thermosetting resin and also utilizes the inner-via-hole connection. This makes it possible to mount circuit components with high density and also allows high heat dissipation. Therefore, the present invention provides a highly reliable circuit component built-in module with circuit components mounted with high density.
Furthermore, it is possible to mount circuit components with higher density by making the circuit component built-in module of the present invention in a multilayered structure.
Furthermore, in the circuit component built-in module of the present invention, the heat conductivity, the coefficient of linear expansion, the dielectric constant or the like of the insulating substrate can be controlled by selecting a suitable inorganic filler. Therefore, in the circuit component built-in module of the present invention, it is possible to equalize substantially the coefficient of linear expansion of the insulating substrate with that of the semiconductor device, so that the present invention is preferably used as a circuit component built-in module in which a semiconductor device is built-in. Furthermore, the heat conductivity of the insulating substrate can be improved so that the present invention is preferably used as a circuit component built-in module in which a component that requires heat dissipation such as a semiconductor device is built-in. Furthermore, it is possible to reduce the dielectric constant of the insulating substrate, so that the present invention is preferably used as a circuit component built-in module for high frequency circuits.
According to the methods for producing a circuit component built-in module of the present invention, the above-described circuit component built-in module can be produced easily.
Furthermore, according to the methods for producing a circuit component built-in module of the present invention, wiring patterns can be buried in the insulating substrate by using a release film provided with the wiring patterns. Therefore, a circuit component built-in module having a smooth surface can be obtained. Thus, when additional circuit components are mounted on the wiring patterns on the surface, a circuit component built-in module having circuit components mounted with higher density can be obtained.
These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.